Brake shoe grinder



yJune 17, 1941. E C, BROXON 2,246,290

BRAKE SHOE GRINDER Filed March/6', 1959 2 sheets-sheet 1 INVENTOR. ERRETT C. BROXON.

ATTORNEY.

`une 17, 1941. E, C. BROXQN 2,246,290

BRAKE SHOE GRINDER Filed March 6, 1939 2 Sheets-Sheet 2 INVENTOR. ERRETT C. BROXON.

Patented June 17, 1941 UNITED STATES PATENT OFFICE BRAKE SHOE GRINDER Errett C. Broxon, Cincinnati, Ohio Application March 6, 1939,v Serial No. 260,062 7 Claims. (o1. 5'1-124) My improved invention relates to a grinder for truing and dressing brake shoes, that is, the brake band material after it is applied to the metal shoe. y

Present brake shoes are of metal with a suitable material applied to the braking surface. This brake material may vary in thicknessI and its surface may be uneven due to drilling and assembly operation. Therefore to obtain maximum eiliciency from the brakes, the braking surface of the shoe must be trued up. Also metal shoes often distort in use causing the surface of the shoe to depart from a true arc.

In the truing of the brake shoe, it is also necessary to skive the ends of the braking material for eflicient operation of the brakes. Due to the fact that brake drums vary in size on various automobiles, with a consequent wide variation in shoe diameters, and widths, I have so designed my machine to accommodate brake shoes of all sizes with simple means for changing from one size to any other size. Y

The object of my invention is to provide a machine for accurately grinding the surface of a brake shoe. A further object is to provide means for readily locating and clamping the shoey on a support in proper relation to the grinding Wheel for accurately truing the shoe. A further object is to provide means for quickly and accurately changing the machine from grinding one diameter of shoe to a diameter of a different shoe. A further object is to provide means for moving the grinding wheel toward the shoe for skiving the ends of the shoe. A still further object isI to provide means for adjusting the grinding wheel relative to the support for grinding shoes either oversize or undersize of the standard diameter of shoes.

My invention will be further readily understood from the following description and claims, and from the drawings, in which latter:

Fig. 1, is a plan view of my improved machine.

Fig. 2, is a side elevation of the same.

Fig. 3, is a front view of the grinding wheel and guard, taken in the plane of the line 3-3 of Fig. 2.

Fig. 4, is an enlarged section of a portion of the machine, taken in the plane of the line 4--4 of Fig. 1.

Fig. 5, is a detail section, taken in the plane of the line 5--5 of Fig. 4.

Fig. 6, is a plan view of the base, partly in section, taken in the plane of the line 6-6 of Fig. 2.

Fig. 7, is a vertical section of the same, taken in the plane of the line 'I-l of Fig. 6, and;

Fig. 8, is a side view of a brake shoe.

My improved machine comprises a base II, provided with guideways I2 for the feet I3 of a motor I4. 'I'he motor is movable endwise on the guides and is held thereon by gibs I5. A rod I6 extends through the base and has a threaded connection lI8 with a lug I9 depending from the motor. An indicating knob 20 is secured to the outer end of the rod and has suitable markings on its periphery to register with a pin 2l extending from the base, whereby the motor can be moved a measured distance by turning the knob. A spring '22 secured to the lug I9 andthe base normally retains the motor in its rearwardl position limited by the knob 20 bearing against the base. Means are provided for moving the motor and grinding wheel forward when it is desired to skive the ends of the shoe. Such means comprises a handle 23 journaled in the base and extending into an aperture 24 in a lever 25. The lever 25 is pivoted on a bolt 26 and has its other end pivoted to an extension 21 of the lug I9 as at 28. Thus forward movement of the handle will cause the motor to move forward against the pull of the spring 22.

Secured to the motor shaft is a grinding wheel 29, which in the present disclosure comprises an emery disc 30 secured to a disc 3I having fins 32 to form fan blades. While I have shown an emery disc, it is apparent that any suitable grinding wheel may be used. A housing 33 surrounds the grinding wheel and is suitably bolted to the motor. This housing forms a dust collector and the fan blades 32 force the grinding dust out of the port 34 to any suitable container. A cover 35 is secured to the housing and has a sufficiently large opening 36 therein to permit grinding the largest brake shoes. The forward surface of the base II is provided with a series of holes 46, 4I, 42, 43, 44, 45, 46, 41 and 48 respectively positioned from the face of the grinding wheel so that the distance from the center of each hole to the grinding face will respectively accommodate brake shoes of nine, ten, eleven, twelve, thirteen, fourteen, fifteen, sixteen and seventeen inch diameters.

A brake shoe supporting structure 50 comprises a base 5I having a pin 52 extending downward and arranged to be received in any one of the holes 40 to 48 depending on the diameter of the shoe to be ground. Said holes form a bearing for locating the supporting structure, and permit the structure to be moved in an arc.

`An endwise movable clamping bar 53 is supported on a boss 54 extending upwardly from the base 5I and slides in a guide in the boss 54. A plate 55 is bolted to the boss to maintain the bar 53 in position. A screw 56 is threaded into the plate 55 and bears against the bar 53 to lock the bar 53 in any desired position. The bar 53 is provided with a rack 51 and a pinion gear 58 meshes with the rack 51, the shaft of which is journaled in the plate 55. A handwheel 59 is secured to the shaft to provide means for rotating the gear 58. A support 60 extendsI upwardly from the base 5I to further support the sliding bar 53.

valignment with `the pin 52.

The end of the bar 53 has a wide supporting flange 62 arranged to support the flange 63 of a brake shoe 64. A Y clamp 65 is pivoted to the bar as at 66 and has pins or studs 61 near each end of the Y. A Ystud 68 having a handwheel 69 is received through an enlarged aperture in the clamp and is threaded into the bar 53; A resilient washer 16 is positioned on the stud 68 between the clamp 65 and the 53 to normally raise the clamp 65 when the handwheel 69 is released from clamping position.

A pair of fingers have racks 16 along one face thereof, said fingers being positioned at right angles to each other and sliding one above the other in a support 11 having the center of the cross movement of the ngers 15 in axial A cap 18 bolted to thesupport 11 retains theV ngers in the support 11. A pinion 19 meshes with both` racks 16 of the fingers 15 for moving the fingers 15 equally in orout. A handwheel 80 is secured to the pinion shaft.

In operating my improved machine, the pin 52 of the supporting structure 50 is placedin one of the holes 40 to 48 which corresponds to the diameter of the brake shoe 64 to be ground. The shoe 64 is then placed on the flange 62 with the radial flange 63 of the shoe 64 under the pins 61 but not clamped in place. The bar 53 -is moved forward to place the shoe 64'in close proximity to the grinding wheel 29. The handwheel 80 is then rotated to move the fingers 15 forward to contact the inner face of the brake shoe 64 and center it relative to the point of pivot. It will be noted that the fingers 15 cross Adirectly over the centerline of the pivot pin 52. The fingers 15 are moved forward to bring the -brake shoe 64 against the grinding wheel 29. The handwheel 69 is rotated to clamp the shoe 64 on the support in correct grinding position. A handle 8| extends from the supporting structure 56 to move the support with the vshoe l64 thereon through an arc, so that the entire surface of the shoe 64 is dressed to a true diameter. As the grinding takes place the handwheel 59 can be rotated to move the shoe 64 closer to the grinding wheel 29, to take the desired cuts. The radius remains the same as the point of pivot is not changed. When the entire surface of the shoe 64 has been dressed, ,it is desirable to skive the ends of the shoe 64. `This is accomplished by holding the sup-port in such `position that the end of the shoe 64 contacts the grinding wheel 29. The handle 23 is then pulled forward, moving the grinding wheel 29 against the shoe 64, thus grinding the tapered `face 82 onthe end of the shoe 64.

If it is desired to grind a shoe over'or under the Ystandard size, it can be accomplished accurately by merely turning the knob to register the-proper marking on the knob 26' with the pointer 2| to move the grinding wheel-29 backward or forward as the case may be to obtain the desired grinding radius. Y

It-will be noted from the foregoing that my improved machine can'be quickly and ,accurately adapted for shoes 64 of any diameter within the range of the machine by merely moving the supporting structure 50 to the hole of .the .correct diameter. n

Having thus fully 'described my invention, Ywhat I claim as new and desire to secure by Letters Patent,- is: i

1. In a device of the character described, the combination of a rotatable abrasive element, a base having a plurality of staggered holes therein, and means for supporting a brake shoe in abrading relation with said element, a pin projecting from said means, said pin being insertable into each of said holes whereby said means may be rotated with respect to said base about v the axis of any preselected hole.

2. A machine for finishing brake shoes comprisinga base, and abrading element supported thereby, a brake shoe clamping arm pivotally supported by said base, said arm having a pair of guideways, a pair of brake shoe locating ngers one guided by each of said guideways and means interconnecting said lingers for jointly moving the same along said guideways.

3. In a device of the character described, the combination, of a base, an abrasive member supported thereby, means pivotally supported by said base for clamping a brake shoe in abrading `relation with said member, a pair of arms each carrying a rack supported thereby, and a single pinion `engaging both of said racks whereby said arms may be simultaneously actuated and one of each arm constantly maintain equidistant from the axis about which said rst-named means pivots.

4. In a device of the character described, the combination of a base, an abrasive member supported thereby, means pivotally supported by said base for clamping a brake shoe in abrading relation with said abrading member, a pair of arms supported by said means for locating a brake shoe with respect to said means, and gearing interconnecting said arms whereby actuation of said gearing simultaneously actuates each of said arms to the same degree.

5. In -a device of the character described, the combination of Van abrasive element, abase member, and a member for rotatably supporting a brake shoe in abrading relation with said element,-one of said members havin-g a plurality of staggered openings therein and the other of said members vhaving a pin adapted for reception by each of said openings whereby said members maybe rotated relatively to each other about the axis of any preselected opening.

6. In a Adevice of the character described, a base, an abrasive element supported thereby, means pivotally supported by said base for supporting a brake shoe in abrading relation with said element, said means having a pair of rectilinear Vguideways stationary relatively thereto, a pair of brake shoe locating arms each guided by one of saidguideways and means for simultaneously actuating said arms relatively to said guide- Ways whereby one end of each of said arms is constantly equidistant from the axis about which said inst-named means pivots.

'7. Ina device of `the character described, the combination of a rotatable abrading element, a base, and a member adapted. for supporting a brake shoe in abrading relation with a radial face of said wheel, said base having therein openings disposed other than on a line perpendicular to'said face, said member having a projection adapted for reception of any of said openings whereby the brake shoe maybe rotated about the axis of any preselected opening in contact with different portions of said abrading element.

ERRETT C. BROXON. 

